1. Field of the Invention
The present invention relates to pressure responsive switches, and more particularly, to a pressure responsive mechanical switch which may only be activated when certain preselected pressure conditions are met.
2. Description of the Prior Art
The operation of an integral rocket-ramjet engine on a high speed vehicle is characterized by a first rocket propulsion phase which boosts the vehicle to ramjet operating speed. The second phase of operation is a transitional phase which is preparatory for a third phase. During the third phase of operation, the vehicle is operated as a ramjet, with air being taken in from the external atmosphere via air inlet ports located on the forward position of the vehicle structure. However, prior to ramjet operation, during the rocket propulsion phase, these forward ports are sealed shut by port covers.
During the transitional phase between the rocket propulsion phase and the ramjet phase, explosive squibs are detonated which blow the port covers out of the forward ports thereby allowing air to flow into the ramjet combustion chamber. Detonation of these squibs occurs after pressure within the rocket fuel chamber has decreased due to consumption of the rocket fuel and when pressure increases within the air inlets due to increased speed of the vehicle.
Presently, this is accomploshed by sensors which are disposed to monitor the salient pressure conditions. The sensors are coupled to electronic logic circuitry which in turn is coupled to a squib detonation circuit. The logic and sensor systems are relatively expensive, must be coupled to an external power source, and are subject to failure resultant to inadvertent damage inflicted upon the delicate electronic components thereof.
The present invention overcomes the problem associated with the prior art by providing a pressure-responsive mechanical switch which is durable, relatively inexpensive to manufacture, and which does not require an external power source.